Oops Concepts In Java
Cancel
-
+
Oops concept in java
- 1.The benefits of the Object Orientation are: ( choose two )
- A.
Inheritance
- B.
Flexibility
- C.
Maintainability
- D.
Polymorphism
- 2.
- A.
Compile error
- B.
2
- C.
4
- D.
No Output
- 3.HAS-A relationships are based on inheritance, rather than usage.
- A.
True
- B.
False
- 4.
- A.
By adding argument "int size" to the method book at line number 3.
- B.
By removing argument '2' at line number 18.
- C.
By creating object of "SuperHotel" subclass at line 17 & calling book(2) from it at line 18
- D.
No correction needed.
- 5.Given below the sample code : import java.io.IOException; class Example7 { public float Twin(float x, float y) throws IOException { return 0; } } class SubExample7 extends Example7 { float Twin(float x, float y) { return 0; } } How can we correct above code ? (choose two)
- A.
No need for correction.
- B.
By changing the method's argument name.
- C.
By removing overridden method 's access specifier(i.e public).
- D.
By adding access specifier 'public' to the overriding method.
- 6.In Java, the actual method executed is determined by the type of the object and not the type of the reference.
- A.
True
- B.
False
- 7.The methods in class object are(choose four)
- A.
Clone
- B.
Notify
- C.
Concat
- D.
Wait
- E.
Equals
- F.
Compare
- 8.Array or collection of superclass references can be used to access a mixture of superclass and subclass objects.
- A.
True
- B.
False
- 9.
- A.
By placing overriding method into subclass.
- B.
By changing the name of the class.
- C.
By replacing overloading from overriding.
- D.
By changing the name of the arguments.
- 10.A class can inherit instance variables and methods from a more abstract superclass.
- A.
True
- B.
False
- 11.At run-time, a Java program is nothing more than objects ‘talking’ to ___________.
- A.
Other objects
- B.
Other metods
- C.
Other classes
- D.
Other binders
- 12.If you do not have access to the source code for a class, but you want to change the way a method of that class works, then could you use subclassing to do that that is to extend the “bad” class and override the method with your own better code?
- A.
True
- B.
False
- 13.The relation between Car and Owner or BankAccount and Customer is example for
- A.
Aggregation
- B.
Composition
- C.
Association
- D.
None
- 14.Aggregation is a special form of association.
- A.
True
- B.
False
- 15.Subclassing polymorphism is sometimes called “true polymorphism”.
- A.
True
- B.
False
- 16.A method defined in a superclass is redefined in a subclass with an identical method signature is called___________.
- A.
Method overloading
- B.
Method overriding
- C.
Dynamic binding
- D.
Late binding
- 17.
- A.
Int a
- B.
Long b
- C.
Long a
- D.
Error
- 18.An interface cannot have an inner class.
- A.
True
- B.
False
- 19.Polymorphism is one interface with __________.
- A.
Single method
- B.
Multiple methods
- C.
Multiple record
- D.
Single record
- 20.Method overloading is done during _______.
- A.
Runtime
- B.
Dynamic binding
- C.
Program compilation
- D.
Late binding
- 21.Interfaces are fast as it requires extra indirection to find corresponding method in the actual class.
- A.
True
- B.
False
- 22.Ad hoc polymorphism is ____________.
- A.
Method Overloading
- B.
Method Overriding
- C.
Subclassing polymorphism
- D.
Dynamic binding
- 23.The inheriting class cannot override the definition of existing methods by providing its own implementation.
- A.
True
- B.
False
- 24.The ability to make changes in your implementation code without breaking the code of others who use your code is a key benefit of _______________.
- A.
Extensibility
- B.
Polymorphism
- C.
Inheritance
- D.
Encapsulation
- 25.Every class in Java is a subclass of class _____________.
- A.
Inheritance
- B.
Object
- C.
Exception
- D.
ArrayList
- 26.Consider the code below and choose the correct option. class GameShape { public void displayShape() { System.out.println("displaying shape"); } // more code } class PlayerPiece extends GameShape { public void movePiece() { System.out.println("moving game piece"); } // more code } public class TestShapes { public static void main (String[] args) { PlayerPiece shape = new PlayerPiece(); shape.displayShape(); shape.movePiece(); } }
- A.
PlayingPiece class inherits the generic movePiece() method
- B.
PlayingPiece class inherits the generic displayShape() method
- C.
GameShape class inherits the generic displayShape() method
- D.
GameShape class inherits the generic movePiece() method
- 27.The two most common reasons to use inheritance are( choose 2)
- A.
To promote code reuse
- B.
To use abstraction
- C.
To use interface
- D.
To use polymorphism
- 28.A class is not an object. But it is used to construct objects.
- A.
True
- B.
False
- 29.Examples of class are( choose 3)
- A.
White
- B.
Length
- C.
Classroom
- D.
Car
- E.
Person
- 30.In OO, the concept of IS-A is based on
- A.
Class inheritance
- B.
Interface implementation.
- C.
Both
- D.
None
Back to top
